Multiscale thermo-chemo-mechanical modeling of early-age damage in cement-based materials

Purpose To investigate early-age damage progression in heterogeneous cementitious materials (CBMs), such as mortar and concrete. The study aims to model the coupled thermochemo-mechanical behavior, focusing on the premise that degradation occurs exclusively within the cement paste due to stresses induced by hydration-driven microstructural evolution, ultimately identifying potential inter-aggregate cracking zones in macroscopic structures. Design/methodology/approach A multiscale computational framework is proposed, coupling an enhanced cement paste damage model with a two-scale Finite Element (FE2) approach using a representative volume element (RVE) to capture heterogeneity. The core is the adapted Direct FE2 (DFE2) method, which uses Multipoint Constraint (MPC) equations to directly link the RVE and macroscopic element degrees of freedom, resulting in a unified, single-level solution strategy. Findings The DFE2 methodology successfully integrates all essential material properties (thermal, chemical and mechanical) and constitutive laws defined at the RVE level, accurately capturing the complex, coupled effects of hydration and damage. This robust computational model provides high-fidelity analysis of the structural component's response and reliably identifies critical regions prone to early-age cracking development within the CBM structure. Originality/value The primary value lies in developing a unified, single-level multiscale modeling strategy for early-age CBMs, which efficiently solves the highly coupled thermochemo-mechanical problem without traditional nested loops. The work refines existing damage modeling to explicitly include microstructural changes during hydration and provides a robust, streamlined computational platform implemented in Abaqus using Python scripts and Fortran subroutines (UMAT, UMATH and UEXPAND).